When a transition between a normal operation state and a standby state in which power consumption is lower than power consumption in the normal operation state is made in a semiconductor device, there is a possibility that a significant drop in voltage caused by a change in load will lead to malfunction.
Accordingly, when a transition between a power-on reset period or a standby state and a normal operation state is made, the adoption of the technique of, for example, changing a frequency of a clock signal step by step for preventing a sudden change in power supply current is proposed.
Japanese Laid-open Patent Publication No. 2005-339310
Japanese Laid-open Patent Publication No. 2003-272380
However, access to a circuit the operation state of which is controlled takes various forms. If an operation state is not controlled according to actual access, then a malfunction may occur in the circuit. For example, if access to a circuit is frequently interrupted and a low power consumption operation state, such as a standby state, and a normal operation state are frequently repeated, then a malfunction may occur in the circuit due to power supply noise.